526Writing off expenditure for periods when building not used as qualifying dwelling-house
(1)This section applies if for any period or periods between—
(a)the time when the whole or a part of the building was first used for any purpose, and
(b)the time when the residue of qualifying expenditure attributable to a dwelling-house falls to be ascertained,
the building or part has not been a qualifying dwelling-house.
(2)An amount equal to the notional writing-down allowances for the period or periods is written off at the time when the residue falls to be ascertained.
(3)The notional writing-down allowances are the allowances that would have been made for the period or periods in question (if the building or part had remained a qualifying dwelling-house), at such rate or rates as would have been appropriate, having regard to any relevant sale.
(4)In subsection (3) “relevant sale” means a sale of the relevant interest as a result of which a balancing adjustment falls to be made under section 513.